Process for removing aromatics from water used in processing coal tar

Abstract

A process for treating water used in a coal tar process is described. The process involves treating the water with extraction with an extraction agent or adsorption with an adsorbent. The extraction agent includes at least one of amphiphilic block copolymers, cyclodextrins, functionalized cyclodextrins, and soluble cyclodextrin-functionalized polymers, and the adsorbent includes insoluble cyclodextrin-functionalized polymers, exfoliated graphite oxide, thermally exfoliated graphite oxide or intercalated graphite compounds.

What is claimed is: 
     
         1 . A process for treating water used in a coal tar process comprising:
 providing a coal tar stream;   separating the coal tar stream into at least two fractions;   performing at least one process utilizing water on the coal tar stream or at least one fraction, the water containing coal tar aromatic compounds after performing the process, the coal tar aromatic compounds comprising polynuclear aromatic compounds, oxygen containing aromatic compounds, nitrogen containing aromatic compounds, or sulfur containing aromatic compounds;   removing at least one coal tar aromatic compound from the water containing coal tar aromatic compounds by extraction with an extraction agent or adsorption with an adsorbent to form a treated coal tar process water stream, the extraction agent comprising at least one of amphiphilic block copolymers, inclusion complexes of poly(methyl methacrylate) and polycyclic aromatic hydrocarbons, cyclodextrins, functionalized cyclodextrins, and soluble cyclodextrin-functionalized polymers, and the adsorbent comprising insoluble cyclodextrin-functionalized polymers, exfoliated graphite oxide, thermally exfoliated graphite oxide or intercalated graphite compounds.   
     
     
         2 . The process of  claim 1  wherein the at least one process utilizing water comprises extraction, steam gasification, steam reforming, washing, or combinations thereof. 
     
     
         3 . The process of  claim 1  wherein the extraction agent is a water soluble extraction agent. 
     
     
         4 . The process of  claim 1  wherein the extraction agent comprises the amphiphilic block copolymer, and wherein the amphiphilic block copolymer comprises at least two blocks selected from polyethylene oxide blocks, polypropylene oxide blocks, butylene oxide blocks, silicone blocks, urethane blocks, polyurethane ionomer blocks, acrylate ionomer blocks, polymethylacryate blocks, polyacrylic acid blocks, and polyvinylidene chloride blocks. 
     
     
         5 . The process of  claim 1  wherein the extraction agent further comprises an ionic liquid, or a supercritical fluid, or both. 
     
     
         6 . The process of  claim 5  wherein the extraction agent comprises the ionic liquid, and wherein the ionic liquid is selected from imidazolium-based ionic liquid, pyrrolidinium-based ionic liquid, pyridinium-based ionic liquid, sulphonium-based ionic liquids, phosphonium-based ionic liquids, and ammonium-based ionic liquids. 
     
     
         7 . The process of  claim 5  wherein the extraction agent comprises the supercritical fluid, and wherein the supercritical fluid comprises supercritical carbon dioxide, supercritical ammonia, supercritical ethane, supercritical propane, supercritical butane, supercritical water, or combinations thereof. 
     
     
         8 . The process of  claim 7  wherein the supercritical fluid is the supercritical ammonia or supercritical carbon dioxide, wherein one of the separated fractions comprises ammonia or carbon dioxide, and wherein the ammonia or carbon dioxide in the one fraction is processed into the supercritical ammonia. 
     
     
         9 . The process of  claim 1  further comprising dissolving the extraction agent in a water-immiscible solvent before contacting the water containing coal tar aromatic compounds with the extraction agent. 
     
     
         10 . The process of  claim 1  wherein at least two coal tar aromatic compounds are removed, and wherein the first coal tar aromatic compound is removed using a first extraction agent and wherein the second coal tar aromatic compound is removed using a second extraction agent after the removal of the first coal tar aromatic compound. 
     
     
         11 . The process of  claim 1  further comprising removing metals from the water. 
     
     
         12 . The process of  claim 11  wherein the metals are removed by precipitation. 
     
     
         13 . The process of  claim 1  wherein the least one coal tar aromatic compound is removed by extraction, and further comprising treating the water with a flocculator before treating the water with the extraction agent. 
     
     
         14 . The process of  claim 1  further comprising purifying the treated coal tar process water stream. 
     
     
         15 . The process of  claim 14  wherein the water is purified in an activated carbon bed, in an absorbent bed, in a stripping column, or combinations thereof. 
     
     
         16 . A process for treating water used in a coal tar process comprising:
 pyrolyzing a coal feed into a coal tar stream and a coke stream;   separating the coal tar stream into at least two fractions;   performing at least one process utilizing water on the coal tar stream or at least one fraction, the water containing coal tar aromatic compounds after performing the process, wherein the at least one process utilizing water comprises extraction, steam gasification, steam reforming, washing, or combinations thereof, the coal tar aromatic compounds comprising polynuclear aromatic compounds, oxygen containing aromatic compounds, nitrogen containing aromatic compounds, or sulfur containing aromatic compounds;   removing at least one coal tar aromatic compound from the water containing coal tar aromatic compounds by extraction with an extraction agent or adsorption with an adsorbent to form a treated coal tar process water stream, the extraction agent comprising at least one of amphiphilic block copolymers, inclusion complexes of poly(methyl methacrylate) and polycyclic aromatic hydrocarbons, cyclodextrins, functionalized cyclodextrins, and soluble cyclodextrin-functionalized polymers, and the adsorbent comprising insoluble cyclodextrin-functionalized polymers, exfoliated graphite oxide, thermally exfoliated graphite oxide or intercalated graphite compounds.   
     
     
         17 . The process of  claim 16  wherein the extraction agent comprises the amphiphilic block copolymer, and wherein the amphiphilic block copolymer comprises at least two blocks selected from polyethylene oxide blocks, polypropylene oxide blocks, butylene oxide blocks, silicone blocks, urethane blocks, polyurethane ionomer blocks, acrylate ionomer blocks, polymethylacryate blocks, polyacrylic acid blocks, and polyvinylidene chloride blocks. 
     
     
         18 . The process of  claim 16  wherein the extraction agent further comprises an ionic liquid, or a supercritical fluid, or both. 
     
     
         19 . The process of  claim 18  wherein the extraction agent comprises the ionic liquid, and wherein the ionic liquid is selected from imidazolium-based ionic liquid, pyrrolidinium-based ionic liquid, pyridinium-based ionic liquid, sulphonium-based ionic liquids, phosphonium-based ionic liquids, and ammonium-based ionic liquids. 
     
     
         20 . The process of  claim 18  wherein the extraction agent comprises the supercritical fluid, and wherein the supercritical fluid comprises supercritical carbon dioxide, supercritical ammonia, supercritical ethane, supercritical propane, supercritical butane, supercritical water, or combinations thereof.